1. Field of the Invention
The present invention relates generally to cruise control systems for vehicles, and more particularly, to a vehicle cruise control system suitable for application to an automobile, for example.
2. Description of the Related Art
For example, during cruise control of an automobile which uses an automatic vehicle-to-vehicle control system (adaptive cruise control), cruise control that changes, for example, the speed and/or other factors of the vehicle according to the particular shape of the road is required for improved driving comfort and safety for the driver. Implementing this requires highly accurate environmental recognition that uses, for example, a car navigation system, cameras, radars, or the like.
The reason is that for example, when a vehicle traveling on a straight road approaches a curved road, there is a need, before making the vehicle travel through the curved road, to detect the start of the curved road in front thereof with a prior understanding of the road shape and control the vehicle for a slowdown to a speed at which the vehicle can travel safely.
Means of recognizing the road shape in this manner includes the steps of, for example: extracting a traveling lane marking from the image information supplied from a camera provided for frontward monitoring in the traveling direction of the vehicle; setting, for example, any three points as measuring points on an image of the edge of the lane marking; defining the coordinates of each measuring point by image processing; calculating the radius of curvature of the lane marking by assigning the coordinates of each point to a general equation of a circle; and identifying the shape of the road having the cornering radius estimated from the above calculation results.
Such technology relating to the recognition of the road shape is disclosed in, for example, JP-A-04-257740.